The invention pertains to tunnel boring machines in general, and more specifically to tunnel boring machines having walking gripper shoes for continuous forwrd movement thereof. Continuous tunnel boring machines are desirable over tunneling machines which bore intermittently due to the fact that the tunnel can be completed in shorter time, thus resulting in lesser machine and machine operator costs.
The following are tunnel boring machines generally known in the art. U.S. Pat. No. 4,915,453, issued to Fikse, discloses a walking gripper shoe tunnel boring machine which carries a rotary cutterhead that can be propelled forwardly substantially continuously by exerting advancing thrust forces on the cutterhead continuously. The advancing thrust forces are first exerted by top and bottom bipods reacting from top and bottom anchor shoes, also known as gripper shoes, in anchored condition against the tunnel wall. Next, side bipods exert advancing force on the tunneling machine frame. These side bipods react from side anchor shoes set in anchored condition against the tunnel wall while the top and bottom anchor shoes "walk" or "float", i.e. slip, relative to the tunneling machine body, and are directly connected by two pairs of anchor shoe setting jacks extending cordwise between the shoes. The side anchor shoes also "walk" or "float" relative to the tunneling machine body and are directly connected by two pairs of transverse jacks extending cordwise between the shoes. The two pairs of upright jacks are located close together longitudinally on the tunnel boring machine and between the two transverse jacks. The above Fikse patent, which is incorporated herein by reference, refers to numerous other tunnel boring machines known in the art including U.S. Pat. No. 3,203,737, issued to Robbins et al, U.S. Pat. No. 3,295,892, issued to Winberg et al, U.S. Pat. No. 3,861,748, issued to Cass, U.S. Pat. No. 3,967,463, issued to Grandori, U.S. Pat. No. 4,420,188, issued to Robbins et al, U.S. Pat. No. 4,548,433, issued to Turner, U.S. Pat. No. 31,511, issued to Spencer, and a tunneling machine operated at Stillwater, Utah, by Traylor Bros. Incorporated, during 1981 and 1982.
Regarding the tunneling machine operated at Stillwater, Utah, this machine had a rotary cutterhead on a machine frame. Twelve advancing jacks interconnected the machine frame with twelve circumferentially disposed anchor shoes, and were employed to advance the machine frame and the cutterhead longitudinally. The twelve anchor shoes were individually gripped against the tunnel wall by short, radially disposed anchoring jacks that interconnected the anchor shoes and the machine frame. The connection between each anchoring jack and the machine frame was a pair of meshed gears that resulted in pivotal movement of the anchor jack with respect to the machine frame when the tunneling machine was advanced on that anchoring jack and anchor shoe.
The above construction was divided into two sets of six anchor shoes and anchoring jacks. One set of six anchor shoes gripped the tunnel wall due to extension of their associated six anchoring jacks, while the other set of six anchor shoes were in an ungripped position on their six retracted anchoring jacks. The advancing jacks between the machine frame and the first set of anchor shoes would be extended to advance the cutterhead and the machine frame. The advancing jacks between the machine frame and the second set of anchor shoes would be retracted to slide the second set of anchor shoes forward. The second set of anchoring jacks would move forward due to their connection to the machine frame.
The Stillwater tunneling machine encountered operating difficulties due to the large number of anchor shoes, anchoring jacks and advancing jacks. Additionally, the geared pivotal connection between the anchoring jacks and the machine frame caused localized stress on the bases of the anchoring jacks. Finally, the pivotal movement of the anchoring jacks relative to the machine frame limited the forward stroke during each anchor shoe gripping.
German Patent No. 2,252,308 discloses an apparatus for the active mechanized support of tunnels which is a shield type machine as opposed to a tunnel boring machine employing a rotary cutterhead. The machine disclosed in this German patent, in one embodiment, employs five extendable shoes and a sixth fixed bottom shoe.
It should be noted that none of the above patents teaches a tunnel boring machine which advances in a substantially continuous manner, with the exception of the machine disclosed in the above Fikse patent. However, the tunnel boring machine disclosed in the Fikse patent suffers from lateral instability due to the fact that the machine is only gripped against the tunnel walls by two diametrically opposite anchor shoes at a time. Specifically, when the top and bottom anchor shoes of Fikse are gripped against the tunnel wall, the cutterhead can skew about a vertical axis. Similarly, while the Fikse tunnel boring machine is anchored by the left and right anchor shoes, the cutterhead can skew about a horizontal axis. Additionally, the central portion of the tunnel boring machine disclosed in the Fikse patent is crowded with the two pairs of upright shoe setting jacks and the two pairs of transverse shoe setting jacks such that the machines central portion is essentially useless for passage of tunneled material, personnel, and equipment therethrough.
A need thus exists for a tunnel boring machine having floating shoes that can continuously bore a tunnel without skewing and with greater efficiency. A need also exists for a tunnel boring machine of the above type having two sets of three anchor shoes floating relative to the frame of the tunnel boring machine and disposed circumferentially thereon, with the anchor shoes of the two sets alternating on the frame. The above orientation of these six anchor shoes allows continuous advance of the tunnel boring machine on three anchor shoes at a time. Thus, the tunnel boring machine of the present invention has increased cutterhead lateral stability due to its three shoe support, with the shoes relatively oriented about 120.degree. apart as opposed to two shoe support with the shoes oriented at 180.degree.. The need also exists for a tunnel boring machine of the above type in which the two sets of three anchor shoes are each interconnected by three pairs of floating gripper cylinders, with each pair of gripper cylinders acting longitudinally on the two anchor shoes that they connect. The above configuration of two sets of three pairs of floating gripper cylinders results in these gripper cylinders being disposed substantially circumferentially around the interior of the tunnel boring machine such that the interior is much more open for passage of tunneled material, personnel, and equipment. The need also exists for a tunnel boring machine of the above type having a small enough number of anchor shoes, gripper cylinders and thrust cylinders such that the machine operates reliably. Finally, a need exists for a tunnel boring machine of the above type in which the gripper cylinders interconnect two anchor shoes, and are not pivotally connected to the machine frame. This configuration reduces localized stress at the point of connection of the gripper cylinder.